In a polyphase rotary field winding for an electric machine in which the conductor lanes are arranged in an offset pattern, hollow spaces usually occur in the winding overhangs, because the conductor lanes of the different phases intersect in the projection from the air gap at least once for each pole pitch. This causes the space in the grooves and winding overhangs to be poorly utilized and the length of the conductor to be increased. If for a high degree of effectiveness a predetermined low conductor resistance is to be maintained, the increase of resistance based on the increased length of the conductor must be compensated by an enlargement of the cross section of the conductor which further increases the volume and weight of the machine.
U.S. Pat. No. 4,398,112 describes a layered conductor for disk armatures and linear motors in which a conductor lane which is stamped from sheet metal represents a winding layer which is inserted into the grooves from the plane of the groove openings in the direction of the groove depth. By inserting identical winding layers of constant conductor height, the conductor lanes can be cost-effectively punched from sheet metal. The winding known from US-PS though shows very short lengths for all conductor lanes; however, since all conductor lanes must have a different distance from the plane of the groove openings, space utilization in the grooves of a 2-phase machine decreases to 50%, in a 3-phase machine to 33.3%, etc. Though the required conductor volume remains low in the known US-PS, the iron volume of the wielding design through which the magnetic flow is passing increases, and with the larger dimensions of the machine, the volume and weight: of the housing increases as well.
With the number of phases, however, increases that portion of the machine which actively contributes to the generation of torque. For machines which are to combine a high degree of effectiveness with high force and power densities, good space utilization at a higher number of phases besides a high number of pole pairs and short conductor lengths is necessary. The share of the housing, of the magnetic yokes, as well as the exciting winding or, resp. the short circuit cage, or in permanently excited machines the magnets as part of the total volume of the electric machine decrease with increasing groove depth. A highly efficient electric machine should therefore possess deep grooves for high power and force densities.
The invention is, therefore, based on the objective to advance the development of a polyphase electric machine in which the armature and the stator lie in a plane opposite to each other which has at least one slotted soft magnetic body to receive prefabricated winding layers in such a manner that, even with multiple phases, good utilization of available space is achieved in the grooves and winding overhangs, and where the lengths of the conductor lanes can be kept short regardless of the depth of the grooves.